A verbal not a visual disorder, which responds to early intervention

The first case of developmental dyslexia was reported by Pringle-Morgan in the BMJ on 7 November 1896.1 Pringle-Morgan, a general practitioner, and Hinshelwood, an ophthalmologist also writing at the turn of the century,2 speculated that such difficulties with reading and writing were due to “congenital word blindness,” and for many years the dominant view was that dyslexia was caused by visual processing deficiencies. There is still continuing interest in the role of visual factors in the aetiology of dyslexia, especially in low level impairments of the visual system.34 However, most research suggests that these are not its cause. The most widely accepted view today is that dyslexia is a verbal deficit5 and can be considered part of the continuum of language disorders. Indeed, converging evidence supports a specific theory, that dyslexic readers have phonological (speech) processing deficits.